Something is weird at the Museum of Natural History. There are hominids in the dinosaur exhibition! Wilson Kipper knows this can't be right, since no hominids lived during the time of the dinosaurs. It turns out his suspicions are correct: someone is altering the exhibition at night. Is it one of the janitors? A new professor or her daughter? Or someone else? Wilson and his friends need to get to the bottom of this messed-up exhibition.